E500(i) – sodium carbonate

E500(i) denotes sodium carbonate (soda ash), a food additive used mainly as an acidity regulator, pH adjuster, anti-caking agent, and thermal processing aid. It is an alkaline inorganic base that, in the presence of food acids or moisture, can indirectly yield CO₂ via conversion to bicarbonate or direct acid–base reaction in specific formulations.

Caloric value (dry product, 100 g)
Approximately 0 kcal per 100 g (inorganic compound with no metabolizable energy; food-use levels are low and application-dependent).

Key constituents
Anhydrous sodium carbonate (Na₂CO₃) with controlled hydrated forms (mono-/decahydrate) depending on grade.
Predominant solution species: sodium (Na⁺) and carbonate (CO₃²⁻).
Trace food-grade impurities within spec (e.g., NaCl, Na₂SO₄), very low acid-insoluble matter, heavy metals below limits.
Low residual moisture; particle size engineered for flow and dosing.

Production process
Natural route: Mining and purification of trona (Na₂CO₃·NaHCO₃·2H₂O) → controlled calcination to Na₂CO₃ → milling/classification.
Synthetic route (Solvay process): NaCl reacts with NH₃ and CO₂ to form NaHCO₃ → calcination to Na₂CO₃ → reagent recovery and refining.
Food-grade finishing: optional dissolution/recrystallization or washing, drying, milling, sieving; quality controls for purity, alkalinity, insolubles, metals, and microbiology; barrier packaging under GMP/HACCP with defined CCPs.

Technological and sensory properties
Raises pH to adjust acidity and modulate color/flavor during baking (enhanced Maillard browning in cookies, pretzels, crackers).
Alkalinity can tenderize doughs and legumes, promote pectin dispersion, and tune texture in alkaline pastas/noodles (kansui systems alongside potassium carbonate).
Acts as anti-caking agent in dry blends; serves as the basic component in some effervescents or leavening systems to generate CO₂.

Food applications
Bakery (cookies, wafers, crackers) for browning and pH control; alkaline baths for pretzels/lye rolls (milder than hydroxides); alkaline noodles/pastas; cocoa processing in alkaline media (more commonly with K₂CO₃); beverages/sauces for pH adjustment; anti-caking in dry mixes.
Typical use levels: from a few hundred ppm to fractions of a percent, depending on matrix and objective.

Nutrition and health
Sodium carbonate contributes sodium but no energy. Excess alkalinity can yield soapy/irritant notes if overdosed; formulations should balance acids and bases. For sodium-sensitive individuals, account for total Na⁺ contributions across the recipe.

Quality and specification themes
Na₂CO₃ purity within spec; controlled loss on drying; neutral odor.
Alkalinity index and solution pH within range; very low insolubles; consistent particle size.
Compliance with contaminant limits; full traceability; manufacturing under GMP/HACCP.

Storage and shelf life
Store cool and dry in well-sealed barrier packs; control ambient RH.
Avoid uptake of atmospheric CO₂ and moisture, which promote surface conversion to bicarbonate and caking.
Apply FIFO rotation and segregate from acids/incompatible materials.

Safety and handling
Concentrated solutions are strongly alkaline and irritant to eyes/skin; use PPE and good handling practices.
In foods, respect “quantum satis” principles and ensure adequate acidulant balance to prevent alkaline residue taste.

Troubleshooting
Soapy/alkaline aftertaste: overdose or insufficient acidulation → reduce Na₂CO₃ and/or increase acid.
Excess browning/bitterness: pH too high or overbake → retune alkalinity and baking profile.
Caking in powders: high RH or poor packaging → upgrade barrier and use desiccants.
Irregular leavening: unbalanced acid–base or unsuitable particle size → rebalance formula and calibrate fineness.

Sustainability and supply chain
The Solvay route is energy- and brine-intensive, with saline coproducts (e.g., CaCl₂); the trona route lowers reagent needs but has mining impacts. Managing process effluents and salts, using recyclable packaging, and reducing waste improve the footprint. Monitoring BOD/COD in effluents reflects best environmental practice.

Cosmetic (INCI) functions
Listed as INCI “Sodium Carbonate.” Primary roles: pH adjuster/buffering agent in aqueous systems; process aid in traditional saponification; sometimes a technical denaturant for raw materials.

Conclusion
E500(i) is a versatile pH regulator and processing aid that, at low and well-balanced doses, improves color, texture, and processability across diverse food matrices. Application quality hinges on purity, moisture management, and precise acid–base balance, alongside robust safety, GMP/HACCP, and environmental practices.

Mini-glossary
pH — Measure of acidity/alkalinity; controlling pH guides flavor, browning, and process safety.
CO₂ — Carbon dioxide; leavening gas generated via acid–base reaction or bicarbonate conversion during baking.
RH — Relative humidity; high RH promotes caking and surface conversions.
INCI — International Nomenclature of Cosmetic Ingredients; standardized naming/functions for cosmetic ingredients.
GMP — Good Manufacturing Practice; hygiene and process controls ensuring consistency, traceability, and quality.
HACCP — Hazard Analysis and Critical Control Points; preventive food-safety system with defined CCPs.
CCP — Critical control point; a step where control prevents, eliminates, or reduces a food-safety hazard to acceptable levels.
FIFO — First in, first out; inventory rotation principle—use older lots first.
BOD/COD — Biochemical/Chemical oxygen demand; indicators of organic load in effluents and potential environmental impact.

Studies

Also used as a test to calibrate the acid in quantitative analysis, co-solvent analysis of silica in cement, glucose analysis in urine and blood, test for the determination of copper, lead, zinc, aluminum, sulfur. Metallographic analysis etc.

For the production of lactulose, it has proved to be effective by considerably reducing the production time (1).

It is used in the preparation and cooking of patties and hamburgers to improve their elasticity, hardness and cohesion (2).

It has been used as an efficient and inexpensive alkaline catalyst for pretreatment of corn straw and lignocellulosic biomass (3).

It is used to improve the tolerance of fruit (in this case pears) to frost damage (4).

It is an anti-inflammatory and is also used as a tooth-cleaning agent (5).

Safety

 A 2024 study warns about the risk of developing cancer with high intakes of emulsifiers, (including E440, Pectin, E471 mono- and diglycerides of fatty acids, carrageenan, E407, sodium carbonate E500) (6).  

The most relevant studies on this ingredient have been selected with a summary of their contents:

Sodium carbonate studies

• Molecular Formula: CNa₂O₃
• Molecular Weight: 105.988 g/mol
• UNII: 45P3261C7T
• CAS: 497-19-8  7542-12-3  6106-20-3  1332-57-6  1314087-39-2  1977561-09-3
• EC Number: 207-838-8  231-420-4
• PubChem Substance ID 24899762
• Beilstein Registry Number 4154566

Synonyms: 

• Disodium carbonate
• Carbonic acid sodium salt
• Sodium carbonate anhydrous
• Anhydrous soda
• CHEBI:29377
• Soda Ash
• Carbonic acid disodium salt
• Trona
• Soda Ash Light 4P
• Suprapur 6395
• Crystol carbonate
• Caswell N0 752
• Natriumkarbonat
• Bisodium carbonate
• Dynamar L 13890
• Soda
• Calcined soda
• sodiumcarbonate
• Sodium carbonate, anhydrous
• Washing soda
• Carbonic acid, disodium salt
• Solvay soda
• Soda, calcined
• Snowlite I
• Light Ash
• V Soda

References___________________________________

(1) Seo YH, Park GW, Han JI. Efficient lactulose production from cheese whey using sodium carbonate. Food Chem. 2015 Apr 15;173:1167-71. doi: 10.1016/j.foodchem.2014.10.109. 

(2) Parlak O, Zorba O, Kurt S. Modelling with response surface methodology of the effects of egg yolk, egg white and sodium carbonate on some textural properties of beef patties. J Food Sci Technol. 2014 Apr;51(4):780-4. doi: 10.1007/s13197-011-0552-4.

Abstract. This study was accomplished to determine the effects of egg yolk, egg white and sodium carbonate on textural properties of beef patties by using Central Composite Design of Response Surface Methodology. Meat patties were prepared using beef, lamb tail fat and spices. Effects of addition of egg yolk powder (0-1%), egg white powder (0-1%) and sodium carbonate (0-1%) on textural properties were studied by using a texture analyzer. The TPA and cutting force tests were measured in the samples. Effects of sodium carbonate were found to be significant (P < 0.01) on springiness, hardness and cohesiveness values of beef patties. However, effects of egg white and egg yolk on the textural parameters were not found significant (P > 0.05). The levels of sodium carbonate up to 0.72% improved the textural properties of beef patties.

(3)Kim I, Rehman MS, Han JI. Enhanced glucose yield and structural characterization of corn stover by sodium carbonate pretreatment. Bioresour Technol. 2014;152:316-20. doi: 10.1016/j.biortech.2013.10.069.

(4) D'Aquino S, Barberis A, Continella A, La Malfa S, Gentile A, Schirra M. Individual and combined effects of postharvest dip treatments with water at 50 degrees C, soy lecithin and sodium carbonate on cold stored cactus pear fruits. Commun Agric Appl Biol Sci. 2012;77(3):207-17.

Abstract. Objective of this study was to evaluate the effect of prestorage dip treatments at 20 degrees C or 50 degrees C alone or with sodium carbonate (SC) and soy lecithin (LEC), either individually or in combination, on weight losses, peel disorders, overall appearance and decay of cactus pears. Fruits were subjected to a simulated Mediterranean fruit fly (medfly) disinfestation by cold quarantine at 2 degrees C for 21 days followed by one week of shelf-life at 20 degrees C. Hot water alone was very effective in reducing peel disorders and decay both during cold storage and shelf-life. SC applied at 20 degrees C showed a weak control of decay and chilling injury, while its effectiveness significantly increased when the solution temperature was set to 50 degrees C. LEC was more effective in preserving freshness during cold storage, but after shelf-life decay incidence in fruit dipped in LEC at 20 degrees C or 50 degrees C was higher than in those dipped in water at 20 degrees C or 50 degrees C, respectively. Significant but moderate differences were detected among treatments in weight loss. After shelf-life, fruit dipped in the heated mixture of SC and LEC showed the lowest incidence of peel disorders and the highest percentage of marketable fruit, although decay incidence was slightly higher than in fruit treated with SC at 50 degrees C. SC and LEC used in combination at 50 degrees C improved fruit tolerance to chilling injury and reduced decay.

(5) Turker SB, Sener ID, Koçak A, Yilmaz S, Ozkan YK. Factors triggering the oral mucosal lesions by complete dentures. Arch Gerontol Geriatr. 2010 Jul-Aug;51(1):100-4. doi: 10.1016/j.archger.2009.09.001. 

(6) Sellem, L., Srour, B., Javaux, G., Chazelas, E., Chassaing, B., Viennois, E., ... & Touvier, M. (2024). Food additive emulsifiers and cancer risk: Results from the French prospective NutriNet-Santé cohort. Plos Medicine, 21(2), e1004338.

Abstract. Emulsifiers are widely used food additives in industrially processed foods to improve texture and enhance shelf-life. Experimental research suggests deleterious effects of emulsifiers on the intestinal microbiota and the metabolome, leading to chronic inflammation and increasing susceptibility to carcinogenesis. However, human epidemiological evidence investigating their association with cancer is nonexistent. This study aimed to assess associations between food additive emulsifiers and cancer risk in a large population-based prospective cohort. Methods and findings: This study included 92,000 adults of the French NutriNet-Santé cohort without prevalent cancer at enrolment (44.5 y [SD: 14.5], 78.8% female, 2009 to 2021). They were followed for an average of 6.7 years [SD: 2.2]. Food additive emulsifier intakes were estimated for participants who provided at least 3 repeated 24-h dietary records linked to comprehensive, brand-specific food composition databases on food additives. Multivariable Cox regressions were conducted to estimate associations between emulsifiers and cancer incidence. Overall, 2,604 incident cancer cases were diagnosed during follow-up (including 750 breast, 322 prostate, and 207 colorectal cancers). Higher intakes of mono- and diglycerides of fatty acids (FAs) (E471) were associated with higher risks of overall cancer (HR high vs. low category = 1.15; 95% CI [1.04, 1.27], p-trend = 0.01), breast cancer (HR = 1.24; 95% CI [1.03, 1.51], p-trend = 0.04), and prostate cancer (HR = 1.46; 95% CI [1.09, 1.97], p-trend = 0.02). In addition, associations with breast cancer risk were observed for higher intakes of total carrageenans (E407 and E407a) (HR = 1.32; 95% CI [1.09, 1.60], p-trend = 0.009) and carrageenan (E407) (HR = 1.28; 95% CI [1.06, 1.56], p-trend = 0.01). No association was detected between any of the emulsifiers and colorectal cancer risk. Several associations with other emulsifiers were observed but were not robust throughout sensitivity analyses. Main limitations include possible exposure measurement errors in emulsifiers intake and potential residual confounding linked to the observational design. Conclusions: In this large prospective cohort, we observed associations between higher intakes of carrageenans and mono- and diglycerides of fatty acids with overall, breast and prostate cancer risk. These results need replication in other populations. They provide new epidemiological evidence on the role of emulsifiers in cancer risk. Copyright: © 2024 Sellem et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.